We propose a four and one-half year program of research to continue investigation of facial expressions of pain and emotion related to acute and chronic dental and orofacial pain. The aims of the research are: 1. To quantify facial expressions of pain and six emotions (sadness, anger, fear, happiness, disgust and contempt) in patients experiencing pain from initial episodes of Temporomandibular Disorders (TMD) or from chronic TMD. 2. To compare facial expressions of pain and emotion in these TMD patients with those of a) normal, pain-free controls, b) patients with acute pulpitis pain, and c) patients with initial episode and recurrent depression. 3. to study the degree to which: a) facial expressions of pain are congruent with self report of pain; b) facial expressions of emotion are congruent with self report measures of emotion, for the subject groups listed above. 4. To observe, in a longitudinal study, how facial expressions of pain and emotion change over the course of a persistent TMD problem. 5. to ascertain how facial expressions of pain and emotion influence clinical judgments. Facial expression will be videotaped under resting conditions and experimentally controlled conditions of painful stimulation and psychological stress. Facial behavior will be coded using EMFACS system for scoring expressions of pain and emotions based on movements of individual facial muscles. Background measures of individual traits, as well as state measures of sadness, anger, fear and happiness will be gathered for comparison with facial expression measures. Initial episode and chronic TMD patients will be studied six months after their first assessment and those initial episode patients who continue to have pain will also be followed up at one year. Studies of clinician judgments will utilize standardized videotape stimuli of subjects undergoing painful stimulation to elicit dentists' judgments regarding pain, emotional state and appropriate treatments. This research should provide information on the relationship of emotion to pain, especially acute and chronic orofacial pain conditions. This work will also enhance knowledge on individual differences in pain behavior; and may increase awareness of nonverbal determinants contributing to clinician's decision-making regarding patient pain levels.